Just got a new car and on the instrument panel it says it takes "premium unleaded"..... is that just a cash grab or does it really make a difference? Would regular hurt it?
Gasoline question
- Thread starter Quest4Less
- Start date
Depending on the car yes it might hurt it. Both my 69 Camaro and my Hayabusa knock like a SOB without premium. Is it a high horsepower car?
Pay now or pay later
Many manufacturers, auto-journalists and (sadly) dealership employees will tell you regular gas is "just fine" because they know this is what most consumers want to hear. Mechanics also know it's guaranteed work for them down the road.
I'm no engineer, but in my experience, and the considerable experience of drivers in my family, using premium fuel is one of the best things you can do for the longterm performance of your car. This is especially true with many late model SOHC/DOCH cars which wring tremendous HP out of smaller engines and make power at high RPMs. With Turbo it's an absolute must. We're not dealing with Dodge Aspens anymore.
I spent parts of my youth in Europe (70's & 80's) where people have been driving smaller hard-working engines for a long time and most wouldn't fathom using gas under 90 Octane - even in the Eastern Bloc countries, high-90's was available & preferred. Today without added protection of lead, high octanes and the additives in premium fuel are even more important.
All I know is neither I nor anyone I know who's stuck to premium has ever had to service the carbs or fuel injectors, or has ever had a car ride or idle rough or faill to start up for any reason other than an bad battery.
It's a couple of extra bucks a week, but compare it to even one stall: just 1 tow $150 - $300, Injector cleaning $400 - $800 (finding a cab at 2AM on Hwy7 & -23 windchill....priceless).
If you buy new cars every 2-3 years you might not care and it likely won't burn you as a warranty issue. But if you're keeping the car in the family for 4+ years, I suggest at least 91 for peace of mind and long term value.
Many manufacturers, auto-journalists and (sadly) dealership employees will tell you regular gas is "just fine" because they know this is what most consumers want to hear. Mechanics also know it's guaranteed work for them down the road.
I'm no engineer, but in my experience, and the considerable experience of drivers in my family, using premium fuel is one of the best things you can do for the longterm performance of your car. This is especially true with many late model SOHC/DOCH cars which wring tremendous HP out of smaller engines and make power at high RPMs. With Turbo it's an absolute must. We're not dealing with Dodge Aspens anymore.
I spent parts of my youth in Europe (70's & 80's) where people have been driving smaller hard-working engines for a long time and most wouldn't fathom using gas under 90 Octane - even in the Eastern Bloc countries, high-90's was available & preferred. Today without added protection of lead, high octanes and the additives in premium fuel are even more important.
All I know is neither I nor anyone I know who's stuck to premium has ever had to service the carbs or fuel injectors, or has ever had a car ride or idle rough or faill to start up for any reason other than an bad battery.
It's a couple of extra bucks a week, but compare it to even one stall: just 1 tow $150 - $300, Injector cleaning $400 - $800 (finding a cab at 2AM on Hwy7 & -23 windchill....priceless).
If you buy new cars every 2-3 years you might not care and it likely won't burn you as a warranty issue. But if you're keeping the car in the family for 4+ years, I suggest at least 91 for peace of mind and long term value.
Look without trying to get into the hows and whys. I would try mid range (89 octane) gas. If you get by without a knock then you should be ok. But also run a tank or two of premium and compare gas milage between that and the mid-grade.
This topic comes up every once in a while and it's always funny to see what people think about this issue.
First off, high octane will do nothing to improve peformance of your engine if the engine doesn't need it. Octane is not some energy boost for your engine. Nor will octane help your engine run cleaner, or anything else.
Nor does it have anything to do with a lead replacement. Lead was added to gas years ago to act as a valve lubricant, and to (supposedly) protect valve seats. Today's cylinder heads are such that they have hardened valve seats and coated valves and do not need lead or any sort of lead replacement. Even my 75 Triumph which supposedly needed lead in the fuel does not need lead as it turns out.
Octane works simply to prevent premature detonation of the gasoline during the compression stroke of the engine. Gasolines with lower Octane will fire during the compression stroke slightly ahead of the spark plug and the result is engine knock which is very very hard on your engine.
Basically, there are two things that as far as I am aware cause knock. 1. is higher compression ratios, and 2. is if the timing is too far advanced. Compression ratio is not adjustable it refers to the ratio of the volume in the cylinder when the piston is at the bottom of its stroke verses the volume in the cylinder at the top of its stroke. You will hear, "it has 10:1 compression" for example. The higher the compression the more the need for high octane fuel.
Timing. Advancing the timing is a great way to get more peformance out of the car. Timing is variable (unlike compression). Used to be with distributors you set the timing at idle and then there was vacuum advances (or even vacuum retards in the case of my Triumph for example), and centrifugal weights inside the distributor all of which varied the timing as you increased or decreased the RPM's of the engine. The faster the RPMs the more you want the timing to advance for better performance. Problem is, as you advance that timing, you need the higher octane fuel to avoid that premature detonation problem and the resulting knock.
So, bottom line, does your car need premium or not?
It depends what the manufacturer says.
If the manufacturer says you need a certain Octane rating then that is what I would use. If they say it will run fine on regular 87, then it will run fine on 87. Putting premium in is a complete and utter waste of money.
If they say it needs 90 Octane, then it needs 90.
The manufacturers are not in bed with the oil companies.
If you put 87 in a car that needs 90, the engine will knock, the knock sensor will sense the knock, the computer will retard the timing and your performance will definitely suffer, though you probably won't be aware because the car will "appear" to drive normally.
Follow what the owners manual says.
First off, high octane will do nothing to improve peformance of your engine if the engine doesn't need it. Octane is not some energy boost for your engine. Nor will octane help your engine run cleaner, or anything else.
Nor does it have anything to do with a lead replacement. Lead was added to gas years ago to act as a valve lubricant, and to (supposedly) protect valve seats. Today's cylinder heads are such that they have hardened valve seats and coated valves and do not need lead or any sort of lead replacement. Even my 75 Triumph which supposedly needed lead in the fuel does not need lead as it turns out.
Octane works simply to prevent premature detonation of the gasoline during the compression stroke of the engine. Gasolines with lower Octane will fire during the compression stroke slightly ahead of the spark plug and the result is engine knock which is very very hard on your engine.
Basically, there are two things that as far as I am aware cause knock. 1. is higher compression ratios, and 2. is if the timing is too far advanced. Compression ratio is not adjustable it refers to the ratio of the volume in the cylinder when the piston is at the bottom of its stroke verses the volume in the cylinder at the top of its stroke. You will hear, "it has 10:1 compression" for example. The higher the compression the more the need for high octane fuel.
Timing. Advancing the timing is a great way to get more peformance out of the car. Timing is variable (unlike compression). Used to be with distributors you set the timing at idle and then there was vacuum advances (or even vacuum retards in the case of my Triumph for example), and centrifugal weights inside the distributor all of which varied the timing as you increased or decreased the RPM's of the engine. The faster the RPMs the more you want the timing to advance for better performance. Problem is, as you advance that timing, you need the higher octane fuel to avoid that premature detonation problem and the resulting knock.
So, bottom line, does your car need premium or not?
It depends what the manufacturer says.
If the manufacturer says you need a certain Octane rating then that is what I would use. If they say it will run fine on regular 87, then it will run fine on 87. Putting premium in is a complete and utter waste of money.
If they say it needs 90 Octane, then it needs 90.
The manufacturers are not in bed with the oil companies.
If you put 87 in a car that needs 90, the engine will knock, the knock sensor will sense the knock, the computer will retard the timing and your performance will definitely suffer, though you probably won't be aware because the car will "appear" to drive normally.
Follow what the owners manual says.
Kirk hit the nail on the head. You probably have a car that squeezes a very high amount of power out of the engine on a horsepower per cubic-inch/litre basis. This usually involves high compression ratios and spark timing that is more advanced. So if your manufacturer calls for premium, use it.
WH
WH
If there is a stamp in your face on the instrument panel that says, "premium unleaded", then you are best to follow the instructions.
Thought lead was added to the gas to increase the octane rating?
Thought lead was added to the gas to increase the octane rating?
Found the answer to my question about lead.
"Midgley demonstrated that the knock was caused by a rapid rise in
pressure after ignition, not during preignition as believed [9]. This
then lead to the long search for antiknock agents, culminating in
tetra ethyl lead [10]. Typical mid-1920s gasolines were 40 - 60 Octane"
More then all you ever wanted to know about the history of gas.
http://www.faqs.org/faqs/autos/gasoline-faq/part1/index.html
"Midgley demonstrated that the knock was caused by a rapid rise in
pressure after ignition, not during preignition as believed [9]. This
then lead to the long search for antiknock agents, culminating in
tetra ethyl lead [10]. Typical mid-1920s gasolines were 40 - 60 Octane"
More then all you ever wanted to know about the history of gas.
http://www.faqs.org/faqs/autos/gasoline-faq/part1/index.html
Thanks
Thanks for all the tips... It's a turbo so I'll go with the label and use premium to be safe.
Thanks for all the tips... It's a turbo so I'll go with the label and use premium to be safe.
Spuds they are definitely not in bed together...although I think they might be making out in the back seat.Spuds said:
gypsy
As you noted in a later post lead was added to gasoline as an antiknock compound. Captain Kirk is right though that it also is a lubricant, or at least the lead compounds left behind after combustion tend to lubricate valve stems, rings etc. When it was introduced they noticed that engine life went up measureably.KBear said:
Modern engines haven't needed the lead for a very long time as modern alloys are much stronger/harder.
I agree with pretty much everything else Kirk says. A modern computer-controlled engine will retard its timing in an attempt to compensate for low octane. It may or may not be fully succesful, but performance will likely suffer.
Long term exposure to knock can cause internal damage to the engine. So if they recommend high octane, use it. One thing not mentioned here is that failure to use it when recommended can also void a warranty, if they can prove it.
Do a search as this topic has been addressed before.
The engine damage that people refer to, but do not describe in detail would be ovaling of the cylinders, cracked piston skirts, cracked rings.
Use synthetic oil with your turbo. Prevents coking of the oil on the turbo bearings.
The engine damage that people refer to, but do not describe in detail would be ovaling of the cylinders, cracked piston skirts, cracked rings.
Use synthetic oil with your turbo. Prevents coking of the oil on the turbo bearings.
I agree that there is no benefit to added octane unless your car is calibrated for it, it will not give you extra power or anything. On the other hand, the oil companies seem to claim that it is more than just octane that differentiates premium from regular, they put better additives in. Hard to say whether that makes sense and is worthwhile, or if it is just marketing.
